1. Field of Invention
The present invention relates to a method for manufacturing a semiconductor device applying a nanoimprinting method.
2. Description of the Related Art
In manufacturing a semiconductor device, patterning is generally carried out by lithography. However, a mask (a photomask) for exposure which is used in the lithography is extremely expensive, and that is a part of a reason that the cost of the semiconductor device can not be reduced. Recently, the nanoimprinting method by which a pattern is transferred onto a particular layer over a substrate, by pressing a mold having a concavo-convex pattern, has drawn attention.
By using the nanoimprinting method, a pattern can be transferred onto a resist without using a photomask for exposure and a resistmask for lithography can be formed. The reference 1 (Japanese Patent Laid-Open No. 2003-272998) discloses a technique to form a pattern in a photoresist by pressing a mold to the photoresist.
A semiconductor element using a thin semiconductor film such as a thin film transistor (TFT) used for a semiconductor device is formed through various manufacturing steps. Specifically, after an island shaped semiconductor film is formed, a gate insulating film is formed and a gate electrode is formed over the gate insulating film. By using a gate electrode or a patterned resist as a mask, impurities imparting n-type or p-type conductivity are doped to the island shaped semiconductor film so as to form a source region, a drain region, LDD regions, and the like.